1. Field of the Invention
The present invention relates generally to ink cartridges and ink supply systems. In particular, the present invention is directed towards ink cartridges which may be used in combination with ink jet printers, and towards ink supply systems applicable to ink jet printers.
2. Description of Related Art
A known inkjet printer has a recording head from which ink is discharged onto a recording medium, e.g., a sheet of paper, to form images on the recording medium. The recording head is mounted to a carriage, which is configured to reciprocate in a direction perpendicular to a direction in which the recording medium is fed. A known inkjet printer also has an ink tank or an ink cartridge configured to store ink, and to supply ink from the ink tank or the ink cartridge to the recording head. In known inkjet printers, ink cartridges may be removably installed in a cartridge accommodating portion provided on the carriage, or installed in a cartridge accommodating portion at a position separated from the carriage. If the ink cartridges are installed at a position separated from the carriage, ink is supplied from the cartridge accommodating portion to the recording head via a tube.
In a known inkjet printer, the ink cartridge has an ink supply portion configured to supply ink from the inside of the ink cartridge to the recording head, and an air intake portion configured to place the inside of the ink cartridge in fluid communication with the atmosphere when the ink cartridge is installed to the cartridge accommodating portion. Nevertheless, if the air intake portion fails to function as intended, e.g., due to user error, the inside of the ink cartridge may not be in fluid communication with the atmosphere. Moreover, in known inkjet printers, if ink is supplied from the ink cartridge while the inside of the ink cartridge is not in fluid communication with the atmosphere, the pressure inside the ink cartridge may drop.
Furthermore, in a known inkjet printer, the inside of the ink cartridge is depressurized when the ink cartridge is manufactured, and therefore the inside of the ink cartridge is depressurized before the ink cartridge is installed in the printer. In such a case, if fluid communication between the inside of the ink cartridge and the recording head is established via the ink supply portion before fluid communication between the inside of the ink cartridge and the atmosphere via the air intake portion is established, ink may return from the recording head to the ink cartridge because the inside of the ink cartridge is depressurized. If ink returns from the recording head to the ink cartridge, menisci of ink formed in the nozzles of the inkjet head may break, trapping air in the recording head, and resulting in potential printing failure.
Another known inkjet printer has an accommodating portion for an ink cartridge having an ink chamber, an ink supply valve configured to supply ink from the ink chamber, and an air intake portion sealed from the outside of the ink cartridge with a film. The cartridge accommodating portion has a protrusion configured to pierce and break the film, placing the ink chamber in fluid communication with the atmosphere, and an ink supply needle configured to contact and open the ink supply valve to supply ink from the ink chamber. In a known inkjet printer, each of the protrusion and the ink supply needle extends in a direction parallel with the direction in which the ink cartridge is inserted to the cartridge accommodating portion. The protrusion extends further from a base of the cartridge accommodating portion than the ink supply needle extends from the base, and therefore the protrusion pierces and breaks the film before the ink supply needle contacts and opens the ink supply valve.
When the difference between the length of the protrusion and the length of the ink supply needle is small, then when the ink cartridge is inserted to the cartridge accommodating portion at an increased speed, the ink supply needle may contact and open the ink supply valve almost at the same time as when the protrusion pierces and breaks the film, which may cause the return of ink from the recording head. Moreover, when the ink cartridge is inserted to the cartridge accommodating portion at an angled or tilted position, the ink supply needle may contact and open the ink supply valve before the protrusion pierces and breaks the film, which also may cause the return of ink from the recording head.
The protrusion may be lengthened, in an attempt to reduce these problems. Nevertheless, the lengthened protrusion may be broken when the ink cartridge is inserted to the cartridge accommodating portion, especially if the ink cartridge is inserted at an angled or tilted position, which also may result in the return of ink from the recording head.